Fire officials will not release will the substance was, O’Keefe said. The substance was given to FBI investigators in case they want to run tests. The second round of testing was performed by a special National Guard team.

Update at 7:50 p.m.: Paulsen has given the all-clear.

Update at 6:55 p.m.: Paulsen reports from the dais that the haz-mat team’s testing will take perhaps an hour longer, and that the Capitol will remain locked down until they are finished. He does say, however, that lawmakers and others in the building may order food — so long as it’s brought into the Capitol by an official with the Des Moines Fire Department.

The House also has reopened debate, and will continue consideration of the traffic camera ban.

Outside the Statehouse, authorities said that while initial tests by Des Moines Fire Department crews seem to indicate the powder is not dangerous, further testing is planned. It is being performed by officials with the 71st Civil Service Team, an inter-agency cooperative responsible for dealing with potentially hazardous situations like this.

“With the sensitivity of government, it’s a realistic threat,” said Brian O’Keefe with the Des Moines Fire Department. “That’s why we’re going to this level of security and testing.”

Officials examine the hazardous letters. (Rodney White/The Register)

Update at 6 p.m.: House Speaker Kraig Paulsen reports that initial tests completed by the haz-mat team indicates the substance found in a letter to state Rep. Ako Abdul-Samad is not hazardous. The team will conduct further tests outside the Capitol in their emergency vehicle, and the Capitol remains locked down until those tests are complete.

Update at 5:50: The haz-mat crew briefly left the Iowa House chambers and now have returned.

Update at 5:35 p.m.: The haz-mat crew has exited the vestibule and returned to Abdul-Samad’s desk, where they now appear to be collecting more material from the ground. Their masks make a loud breathing sound not unlike that of Darth Vader in Star Wars. State lawmakers and staffers — who are not wearing any protective gear — are crowded around, some within an arm’s length of the officials.

Update at 5:30 p.m.: Two hazardous materials officials in bright yellow haz-mat suits and breathing apparatus appeared on the House floor, and went to Abdul-Samad’s desk where they appeared to collect samples of something. They’re now in the vestibule area with Abdul-Samad and his aide.

Update at 5:12 p.m.: The postal inspector and haz-mat team will be arriving in the House chambers shortly to test the mysterious white powder found in a letter received by Rep. Ako Abdul-Samad. The building remains locked down, with perhaps 250 people currently in the House chamber alone.

Update at 4:55 p.m.: A Highway Patrol official just came on the Capitol-wide intercom system asked visitors to remain in the building until further notice.

Update at 4:44 p.m.: A fire truck and ambulance have arrived, and House Speaker Kraig Paulsen told the chamber that “haz mat” was on its way and that the postal inspector has asked everyone to remain in the chamber until a field test on the substance is completed.

Original post: Work in the Iowa House has ground to a halt this afternoon after a state lawmaker received an envelope containing an unknown powder.

Rep. Ako Abdul-Samad received the letter today and apparently opened it on the House floor. The document inside contained threatening language as well as the powder, said House Speaker Kraig Paulsen.

Abdul-Samad, D-Des Moines, is now sitting in a vestibule area of the Capitol, and a postal inspector is on the way to do a field test on the powder substance.

“Apparently they can make whatever determinations at that point, and then we’ll know,” Paulsen said.

Pending the inspector’s arrival, lawmakers and staff are milling around the House chamber, after state police recommended the room and building not be evacuated. The House ceased business at 3:47 p.m. in response to the incident.

“We’re all just kind of hanging loose,” Paulsen said.

Along with Abdul-Samad in the small vestibule linking the House chamber to the second-floor rotunda is his clerk, Mike McRae, Rep. Mark Smith, D-Marshalltown, Rep. Patrick Murphy, D-Dubuque, Paulsen and House Chief Clerk Charlie Smithson. Smithson is holding a plastic bag containing the letter.

Rep. Kevin Koester, R-Ankeny, said he was sitting near Abdul-Samad after the letter had been opened. He said he saw the substance — a white powder — spilled on McRae’s pants. It looked like flour or powdered sugar, he said.